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한정식(Jeong-sik Han),정병훈(Byoung-hun Jeong),김영운(Young-wun Kim),홍진숙(Jinsook Hong),정근우(Keunwoo Chung) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12
고무탄성체가 연료와 접촉하면 저분자량의 고무성분이나 첨가제 등이 연료에 의해 용출되면서 고무의 기계적 물성을 저하시키고 연료의 물성에도 영향을 미치게 된다. 본 연구에서는 고무탄성체 중 밀봉재로 사용되는 고무 오링이 연료와 접촉하고 있을 때 온도에 따라 고무 오링의 기계적 물성치중 영구압축줄음율을 측정하여 변화정도를 추적하고 이를 근거로 고무 오링의 수명을 예측하였다. 고무의 수명예측은 가속열화 시험에 의한 아레니우스 식을 이용하였으며 예측된 수명은 유제의 종류에 따라 20 ℃에서 16년 ~ 394년의 수명을 갖는 것으로 나타났다. When rubber elastomers have contact with fuel, because rubber component and its additive having low molecular weight can flow out, the physical properties of the elastomer and fuel are influenced. This study is about pursuing and measuring the change of compression set, as one of mechanical properties on temperature for sealant rubber O-ring contacted with fuel. We also could predict the life of the rubber elastomers. The life assessment of 16 to 394 years at 20 ℃ by the kinds of fuel could be calculated based on Arrhenius Equation using accelerated degradation test
Membrane proteomic analysis of human mesenchymal stromal cells during adipogenesis
Jeong, Ju Ah,Ko, Kyung-Min,Park, Hyung Soon,Lee, Jinsook,Jang, Cholsoon,Jeon, Choon-Ju,Koh, Gou Young,Kim, Hoeon WILEY-VCH 2007 Proteomics Vol. No.
<P>Mesenchymal stromal cells (MSCs) have proven useful for cell and immune therapy, but the molecular constituents responsible for their functionalities, in particular, those on the plasma membrane, remain largely unknown. Here we employed both gel and nongel based MS to analyze human MSCs' membrane proteome before and after adipogenesis. 2-DE of cells that were pretreated with membrane impermeable fluorescent dyes revealed that both the whole cell proteome and the cell surface subproteome were independent of donors. LC coupled with tandem MS analysis of the plasma membrane-containing fraction allowed us to identify 707 proteins, approximately half of which could be annotated as membrane-related proteins. Of particular interest was a subset of ectodomain-containing membrane-bound proteins that encompass most known surface markers for MSCs, but also contain a multitude of solute carriers and ATPases. Upon adipogenic differentiation, this proteomic profile was amended to include several proteins involved in lipid metabolism and trafficking, at the expense of, most noticeably, ectoenzymes. Our results here provide not only a basis for future studies of MSC-specific molecular mechanisms, but also a molecular inventory for the development of antibody-based cell isolation and identification procedures.</P>
Expression, purification and crystallization of GSK3β in complex with the flavonoid morin
Jeong Seok Cha,Kuglae Kim,Jinsook Ahn,Hyun-Soo Cho 한국구조생물학회 2018 Biodesign Vol.6 No.3
GSK3β is an important kinase that functions in cellular signaling pathways. Morin, a flavonoid that is plentiful in nature, was found as an inhibitor of GSK3β that can reduce tau pathology in vivo and in vitro. To identify how morin inhibits GSK3β, GSK3β protein was overexpressed and purified using affinity and ion exchange chromatography. GSK3β protein was crystallized with morin using hanging drop vapor diffusion method in the presence of 18 % (v/v) PEG 4000, 100 mM sodium citrate (pH 6.5), and 5 % (v/v) 2-propanol at 290 K. X-ray diffraction data was collected to a maximum resolution of 2.14 Å. The crystal belonged to P2 1 , with unit cell parameters a = 67.6 Å, b = 134.4 Å, c = 100.4 Å, α = γ = 90.0°, β = 103.8°.
Ahn, Jinsook,Lee, Dukwon,Jo, Inseong,Jeong, Hyeongseop,Hyun, Jae-Kyung,Woo, Jae-Sung,Choi, Sang-Ho,Ha, Nam-Chul Korean Society for Molecular and Cellular Biology 2020 Molecules and cells Vol.43 No.3
Cryo-electron microscopy (cryo-EM) is now the first choice to determine the high-resolution structures of huge protein complexes. Grids with two-dimensional arrays of holes covered with a carbon film are typically used in cryo-EM. Although semi-automatic plungers are available, notable trial-and-error is still required to obtain a suitable grid specimen. Herein, we introduce a new method to obtain thin ice specimens using real-time measurement of the liquid amounts in cryo-EM grids. The grids for cryo-EM strongly diffracted laser light, and the diffraction intensity of each spot was measurable in real-time. The measured diffraction patterns represented the states of the liquid in the holes due to the curvature of the liquid around them. Using the diffraction patterns, the optimal time point for freezing the grids for cryo-EM was obtained in real-time. This development will help researchers rapidly determine high-resolution protein structures using the limited resource of cryo-EM instrument access.
Lamin Filament Assembly Derived from the Atomic Structure of the Antiparallel Four-Helix Bundle
하남출,Jinsook Ahn,Inseong Jo,Soyeon Jeong,Jinwook Lee 한국분자세포생물학회 2023 Molecules and cells Vol.46 No.5
The nucleoskeletal protein lamin is primarily responsible for the mechanical stability of the nucleus. The lamin assembly process requires the A11, A22, and ACN binding modes of the coiled-coil dimers. Although X-ray crystallography and chemical cross-linking analysis of lamin A/C have provided snapshots of A11 and ACN binding modes, the assembly mechanism of the entire filament remains to be explained. Here, we report a crystal structure of a coil 2 fragment, revealing the A22 interaction at the atomic resolution. The structure showed detailed structural features, indicating that two coiled-coil dimers of the coil 2 subdomain are separated and then re-organized into the antiparallel-four-helix bundle. Furthermore, our findings suggest that the ACN binding mode between coil 1a and the C-terminal part of coil 2 when the A11 tetramers are arranged by the A22 interactions. We propose a full assembly model of lamin A/C with the curvature around the linkers, reconciling the discrepancy between the in situ and in vitro observations. Our model accounts for the balanced elasticity and stiffness of the nuclear envelopes, which is essential in protecting the cellular nucleus from external pressure.
Kim, Jinsook,Song, Insil,Jo, Ara,Shin, Joo-Ho,Cho, Hana,Eoff, Robert L.,Guengerich, F. Peter,Choi, Jeong-Yun American Chemical Society 2014 Chemical research in toxicology Vol.27 No.10
<P/><P>DNA polymerase (pol) ι is the most error-prone among the Y-family polymerases that participate in translesion synthesis (TLS). Pol ι can bypass various DNA lesions, e.g., <I>N</I><SUP>2</SUP>-ethyl(Et)G, <I>O</I><SUP>6</SUP>-methyl(Me)G, 8-oxo-7,8-dihydroguanine (8-oxoG), and an abasic site, though frequently with low fidelity. We assessed the biochemical effects of six reported genetic variations of human pol ι on its TLS properties, using the recombinant pol ι (residues 1–445) proteins and DNA templates containing a G, <I>N</I><SUP>2</SUP>-EtG, <I>O</I><SUP>6</SUP>-MeG, 8-oxoG, or abasic site. The Δ1–25 variant, which is the <I>N</I>-terminal truncation of 25 residues resulting from an initiation codon variant (c.3G > A) and also is the formerly misassigned wild-type, exhibited considerably higher polymerase activity than wild-type with Mg<SUP>2+</SUP> (but not with Mn<SUP>2+</SUP>), coinciding with its steady-state kinetic data showing a ∼10-fold increase in <I>k</I><SUB>cat</SUB>/<I>K</I><SUB>m</SUB> for nucleotide incorporation opposite templates (only with Mg<SUP>2+</SUP>). The R96G variant, which lacks a R96 residue known to interact with the incoming nucleotide, lost much of its polymerase activity, consistent with the kinetic data displaying 5- to 72-fold decreases in <I>k</I><SUB>cat</SUB>/<I>K</I><SUB>m</SUB> for nucleotide incorporation opposite templates either with Mg<SUP>2+</SUP> or Mn<SUP>2+</SUP>, except for that opposite <I>N</I><SUP>2</SUP>-EtG with Mn<SUP>2+</SUP> (showing a 9-fold increase for dCTP incorporation). The Δ1–25 variant bound DNA 20- to 29-fold more tightly than wild-type (with Mg<SUP>2+</SUP>), but the R96G variant bound DNA 2-fold less tightly than wild-type. The DNA-binding affinity of wild-type, but not of the Δ1–25 variant, was ∼7-fold stronger with 0.15 mM Mn<SUP>2+</SUP> than with Mg<SUP>2+</SUP>. The results indicate that the R96G variation severely impairs most of the Mg<SUP>2+</SUP>- and Mn<SUP>2+</SUP>-dependent TLS abilities of pol ι, whereas the Δ1–25 variation selectively and substantially enhances the Mg<SUP>2+</SUP>-dependent TLS capability of pol ι, emphasizing the potential translational importance of these pol ι genetic variations, e.g., individual differences in TLS, mutation, and cancer susceptibility to genotoxic carcinogens.</P>